Multiple Overlapping Thin Slab Acquisition (MOTSA) is a Magnetic Resonance Imaging (MRI) acquisition technique, wherein several overlapping 3D volumes (or “slabs”) are sequentially acquired and combined into a single 3D volume. MOTSA is used for 3D time-of-flight (TOF) MRI intracranial angiography applications, where flow compensated gradient-echo sequences are optimized to favor the vascular signal over that of the surrounding tissues.
In practice, 3D TOF sequences with MOTSA are limited to small slice field of view (FOV) coverage and to low slice resolution in order to keep the scan time clinically relevant (<10 min). The recent developments in MRI acceleration techniques such as the sparse undersampling and iterative reconstruction on TOF (e.g., TOF with sparse undersampling) can provide much needed extra scan time savings that enables larger slice FOV acquisition within acceptable scan time, and thus can potentially overcome the slice FOV coverage limitation of the conventional TOF.
In the prior systems and in the conventional TOF, every overlapping slab is a slice-shifted copy of itself with identical parameters by default. With this, the scan time savings from the advanced MM acceleration techniques can only be utilized toward more slice FOV coverage or remain as is (i.e., keeping the time savings). In reality, though, not all blood vessels are constructed equally, and slice resolution in each of the overlapped slabs should be tailored accordingly. For example, for some applications, more slice resolution may be needed for smaller distal arteries and less may be required for larger, well-defined vessels.